Shock strut fluid adjustment assisting system

ABSTRACT

A shock strut servicing assistance system may comprise a controller including a display, and a tangible, non-transitory memory configured to communicate with the controller. The tangible, non-transitory memory may have instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising calculating, by the controller, a first fluid level, generating, by the controller, a first datum corresponding to the first fluid level, receiving, by the shock strut, a fluid in response to the first datum, calculating, by the controller, a second fluid level, generating, by the controller, a second datum, and storing, by the controller, a final fluid level.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and claims priority to, and thebenefit of U.S. Ser. No. 14/934,924 filed on Nov. 6, 2015, and entitled“SHOCK STRUT FLUID ADJUSTMENT ASSISTING SYSTEM” which is incorporated byreference herein in its entirety.

FIELD

The present disclosure relates to landing gear, and more particularly,to systems and methods for increasing the serviceability of shock strutswithin landing gear.

BACKGROUND

Conventionally, various types of aircraft utilize shock strut assembliesto assist in reducing and managing energy transmitted from landing gearto the structure of an aircraft to which the landing gear is attached.Such shock strut assemblies often feature a piston that compresses afluid within a sealed chamber. The fluid typically includes a gassegment and a liquid segment. Performance of the shock strut assemblymay degrade over time. Such degradation can cause damage to othercomponents of the aircraft, including bearings of the landing gearassembly. With typical single stage shock struts, the aircraft is liftedabove the ground so that the shock strut can be in the fully extendedposition for servicing. Then, the shock strut may be cycled multipletimes in attempt to fully remove any trapped gas internal to the shockstrut during servicing. This can be time consuming and costly.

SUMMARY

A shock strut servicing assistance system may comprise: a controllerincluding a display; and a tangible, non-transitory memory configured tocommunicate with the controller. The tangible, non-transitory memory mayhave instructions stored thereon that, in response to execution by thecontroller, cause the controller to perform operations comprising:calculating, by the controller, a first fluid level; generating, by thecontroller, a first datum corresponding to the first fluid level;receiving, by the shock strut, a fluid in response to the first datum;calculating, by the controller, a second fluid level; generating, by thecontroller, a second datum; and storing, by the controller, a finalfluid level.

In various embodiments, the controller may be in electroniccommunication with a shock strut servicing monitoring system. Anindication may be displayed on the display in response to at least oneof the first datum or the second datum. The second datum may begenerated in response to the second fluid level being greater than athreshold value. The first fluid level and the second fluid level maycorrespond to at least one of a volume of a fluid added to a shock strutduring service or a number of moles of the fluid added to the shockstrut during service. The fluid may comprise at least one of oil or gas.

A method for monitoring a shock strut may include: adjusting, by acontroller, at least one of an oil volume and a gas pressure; detecting,by the controller, at least one of an oil volume loss and a gas numberof moles loss; and generating, by the controller, a signal correspondingto the at least one of the oil volume loss and the gas number of molesloss.

In various embodiments, the controller may receive the at least one ofthe oil volume and the gas pressure from a shock strut servicingmonitoring system (SSSMS). The adjusting may comprise adjusting to anormalized value. The detecting may include comparison of a desiredvalue with an adjusted value of the at least one of the oil volume andthe gas pressure. The signal may be generated by comparing the at leastone of the oil volume loss and the gas number of moles loss with a rangeof threshold values, the range including from 1 to 100 threshold values.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

FIG. 1 illustrates a single stage shock strut for use in landing gear ofan aircraft, in accordance with various embodiments;

FIG. 2 illustrates a loss detection process, in accordance with variousembodiments;

FIG. 3 illustrates an exemplary display in display mode, in accordancewith various embodiments;

FIG. 4 illustrates an exemplary display in servicing mode, in accordancewith various embodiments;

FIG. 5 illustrates an oil level adjustment process, in accordance withvarious embodiments;

FIG. 6 illustrates a gas level adjustment process, in accordance withvarious embodiments;

FIG. 7 illustrates a method for monitoring a shock strut, in accordancewith various embodiments;

FIG. 8 illustrates a process for servicing oil volume within a shockstrut, in accordance with various embodiments; and

FIG. 9 illustrates a process for servicing gas pressure within a shockstrut, in accordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration and their best mode. While these exemplary embodiments aredescribed in sufficient detail to enable those skilled in the art topractice the disclosure, it should be understood that other embodimentsmay be realized and that logical, chemical and mechanical changes may bemade without departing from the spirit and scope of the disclosure.Thus, the detailed description herein is presented for purposes ofillustration only and not of limitation. For example, the steps recitedin any of the method or process descriptions may be executed in anyorder and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact.

System program instructions and/or controller instructions may be loadedonto a non-transitory, tangible computer-readable medium havinginstructions stored thereon that, in response to execution by acontroller, cause the controller to perform various operations. The term“non-transitory” is to be understood to remove only propagatingtransitory signals per se from the claim scope and does not relinquishrights to all standard computer-readable media that are not onlypropagating transitory signals per se. Stated another way, the meaningof the term “non-transitory computer-readable medium” and“non-transitory computer-readable storage medium” should be construed toexclude only those types of transitory computer-readable media whichwere found in In Re Nuijten to fall outside the scope of patentablesubject matter under 35 U.S.C. § 101.

Aircraft landing gear systems in accordance with the present disclosuremay comprise a shock strut. A shock strut may comprise various fluidssuch as oil and gas. Performance of the shock strut may be evaluated bymonitoring aspects of the shock strut, including gas temperature, gaspressure, oil pressure, and stroke of the shock strut at various pointsduring operation of the aircraft. Stroke may refer to a shock strutpiston position. A servicing assistance system may be used in additionto a monitoring system to calculate oil loss and gas loss within a shockstrut. Thus, oil and/or gas may be added to the shock strut during amaintenance process where the monitoring system indicates to ground crewwhen the shock strut has been filled with the appropriate volume of oiland/or pressure of gas. In various embodiments, landing gear of anaircraft may remain on a fixed surface during the shock strut servicingprocess without the need to lift the aircraft. The fixed surface may bea runway, a shop floor, the earth, the ground, or the like, for example.In various embodiments, landing gear of an aircraft may be supported bya jack during the shock strut servicing process without the need to liftthe aircraft. Hence, independent servicing of oil and gas in a shockstrut may be performed and traditional shock strut servicing proceduresmay be greatly simplified.

As used herein an oil level may refer to a volume of oil. As used hereina gas level may refer to the number of moles of gas.

The following nomenclature corresponds to various equations andparameters described in the present disclosure:

Tunable Parameters:

A: Piston area

P_(gas,nom): Shock strut inflation pressure at 20° C. in the fullyextended position

V_(tot,in-air): Shock strut internal volume in the fully extendedposition

V_(oil,nom): Desired oil volume at 20° C.

Internal Parameters:

i: Counter

P_(gas,m@20° C.,i): Computed pressure adjusted to 20° C. in iterationstep ‘i’

P_(gas,m@Tgas): Computed pressure (SSSMS direct output)

P_(gas,m@20° C.): Computed pressure adjusted to 20° C. (SSSMS adjustedoutput)

R: Gas ideal constant

V_(oil,m@20° C.): Computed oil volume adjusted to 20° C. (SSSMS adjustedoutput)

V_(oil,m@Tgas): Computed oil volume (SSSMS direct output)

dT: Integration step

ΔV_(oil@20° C.): Oil volume loss adjusted to 20° C.

Z: Gas compressibility index as a function of gas pressure andtemperature

V_(oil,0@Tgas,0): as Computed oil volume at the onset of servicing

V_(gas,o@Tgas,0): Computed gas volume at the onset of servicing

ΔV_(oil-added@Tgas,0): Computed oil volume added during servicing

ΔV_(oil-added@20C): Computed oil volume added during servicing adjustedto 20° C.

n₀: Number of moles of gas in the shock strut at the onset of servicing

Δn_(gas,added): Number of moles of gas added to the shock strut duringservicing

Sensor Measurements:

{circumflex over (T)}_(gas): Gas temperature

{circumflex over (T)}_(gas,0): Gas temperature at the onset of servicing

Ŝ: Shock strut stroke

Ŝ₀: Shock strut stroke at the onset of servicing

{circumflex over (P)}_(gas): Shock strut pressure

{circumflex over (P)}_(gas,0): Shock strut pressure at the onset ofservicing

Accordingly, with reference to FIG. 1, a landing gear assembly 100 isillustrated. In various embodiments, landing gear assembly 100 comprisesa shock strut 104. Shock strut 104 may be mechanically coupled to awheel assembly 106. In various embodiments, shock strut 104 may beconfigured to absorb and dampen forces transmitted by wheel assembly 106to an aircraft.

Shock strut 104 may comprise, for example, a piston 102 and a cylinder108. Cylinder 108 may be configured to receive piston 102 in a mannerthat allows the two components to telescope together and absorb anddampen forces transmitted by wheel assembly 106.

In various embodiments, a liquid, such as a hydraulic fluid or oil, islocated within cylinder 108. Cylinder 108 and piston 102 may, forexample, be configured to seal such that liquid contained withincylinder 108 is prevented from leaking as piston 102 translates relativeto cylinder 108. Further, cylinder 108 may be configured to contain agas such as nitrogen gas or air. Shock strut 104 may comprise a proximalend and a distal end, wherein the distal end is opposite the proximalend, the distal end being the end of the shock strut closest to a wheelor wheel assembly of a vehicle, such as wheel assembly 106, for example.The air may be positioned above the oil (referred to as an“air-over-oil” arrangement) or vice versa, where the term “above” inthis context means in the direction of the proximal end of the shockstrut. Similarly, cylinder 108 and piston 102 may be sealed such thatgas is prevented from leaking as piston 102 moves relative to cylinder108. As such, shock strut 104 may comprise a pressurized environmentwithin cylinder 108.

Shock strut 104 may further comprise, for example, a gas pressure sensor110. In various embodiments, gas pressure sensor 110 may be capable ofmeasuring the pressure of the gas within shock strut 104 at a desiredtime. For example, gas pressure sensor 110 may measure the gas pressurewithin shock strut 104 before, during, or after take-off, or at anypoint during the duty cycle of shock strut 104.

In various embodiments, shock strut 104 may further comprise, forexample, a gas temperature sensor 112. Gas temperature sensor 112 may becapable of measuring the temperature of the gas within shock strut 104at any point during the duty cycle of shock strut 104.

Similarly, shock strut 104 may comprise an oil pressure sensor 114. Invarious embodiments, oil pressure sensor 114 may be capable of measuringthe pressure of the oil within shock strut 104 at a desired time. Forexample, oil pressure sensor 114 may measure the oil pressure withinshock strut 104 at any point during the duty cycle of shock strut 104.

In various embodiments, shock strut 104 may include various othersensors. Shock strut 104 may include an oil temperature sensor. An oiltemperature sensor may be used to measure the temperature of oil insideof shock strut 104. An oil temperature sensor may aide in determiningthe pressure of oil inside of shock strut 104.

Shock strut 104 may also comprise a position sensor 116. In variousembodiments, position sensor 116 may be capable of measuring theposition of piston 102 relative to cylinder 108, which is conventionallyreferred to as the stroke of shock strut 104 at a desired time. Positionsensor 116 may be configured to measure the position indirectly, forexample, by measuring the orientation of one or more shock strut torquelinks 118 (or other components). For example, position sensor 116 maymeasure the stroke of shock strut 104 at any point during the duty cycleof shock strut 104.

With reference to FIG. 2, loss detection process 200 is illustrated, inaccordance with various embodiments. In various embodiments, lossdetection process 200 may comprise system program instructions and/orcontroller instructions. Loss detection process 200 may be located onhandheld device 302 of FIG. 3. However, it is contemplated that lossdetection process 200 may be located on any controller located on forexample, an aircraft or other vehicle. In various embodiments, lossdetection process 200 may include normalizing process 206, quantifyingprocess 210, and display process 214. In various embodiments, lossdetection process 200 may include shock strut servicing monitoringsystem (SSSMS) 202. However, in various embodiments, loss detectionprocess 200 and SSSMS 202 may comprise two separate processes, whereinloss detection process 200 receives oil volume 204 and/or gas pressure205 from SSSMS 202 as one or more inputs.

With further reference to FIG. 7, a method 700 for monitoring a shockstrut is provided. In various embodiments, shock strut servicingmonitoring system (SSSMS) 202 may quantify oil volume 204 and gaspressure 205. Normalizing process 206 may receive oil volume 204 and gaspressure 205 as one or more inputs from SSSMS 202. Normalizing process206 may use oil volume 204 and gas pressure 205 to calculate normalizedoil volume 208 and normalized gas pressure 209 (see step 701).Normalizing process 206 may use equation 1 and equation 2, below, tocalculate normalized oil volume 208 and normalized gas pressure 209. Asillustrated in FIG. 2, oil volume 204 and gas pressure 205 are adjustedto volume and pressure corresponding to twenty degrees Celsius,respectively. However, it is contemplated that oil volume 204 and gaspressure 205 may be adjusted to any normalized value.

$\begin{matrix}{{V_{{oil},{{m@20}{^\circ}\mspace{14mu}{C.}}} = {V_{{oil},{m@{\hat{T}}_{gas}}}( {1 + {\alpha \times {dT} \times {{sign}( {20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{gas}}}} )}}} )}^{\frac{{20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{gas}}}}}{dT}}}{\underset{\_}{initialization}\text{:}}\mspace{535mu}\{ {{\begin{matrix}{i = 1} \\{{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},i} = P_{{gas},{nom}}},{20{^\circ}{\mspace{11mu}\;}{C.}}} \\\begin{matrix}{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},{i + 1}} = ( {P_{{gas},{m@{\hat{T}}_{gas}}} + 14.7} )} \\{\frac{V_{{tot},{{in} - {air}}} - V_{{oil},{m@{\hat{T}}_{gas}}}}{V_{{tot},{{in} - {air}}} - V_{{oil},{{m@20}{^\circ}\mspace{14mu}{C.}}}} \times} \\{{\frac{( {20 + 273} )}{( {{\hat{T}}_{gas} + 273} )} \times \frac{Q( {P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},i},{20{^\circ}\mspace{14mu}{C.}}} )}{Z( {P_{{gas},{m@{\hat{T}}_{gas}},}{\hat{T}}_{gas}} )}} - 14.7}\end{matrix}\end{matrix}\underset{\_}{Iteration}\text{:}\mspace{580mu}{while}\mspace{14mu}\frac{{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},{i + 1}} - P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},i}}}{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},i}}} \geq {0.001\{ {\begin{matrix}{i = {i + 1}} \\\begin{matrix}{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},{i + 1}} = ( {P_{{gas},{m@{\hat{T}}_{gas}}} + 14.7} )} \\{\frac{V_{{tot},{{in} - {air}}} - V_{{oil},{m@{\hat{T}}_{gas}}}}{V_{{tot},{{in} - {air}}} - V_{{oil},{{m@20}{^\circ}\mspace{14mu}{C.}}}} \times} \\{{\frac{( {20 + 273} )}{( {{\hat{T}}_{gas} + 273} )} \times \frac{Q( {P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},i},{20{^\circ}\mspace{14mu}{C.}}} )}{Z( {P_{{gas},{m@{\hat{T}}_{gas}},}{\hat{T}}_{gas}} )}} - 14.7}\end{matrix}\end{matrix}\mspace{346mu}{End}}\mspace{301mu} }} } & {{Eq}.\mspace{14mu}(1)} \\{P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}}} = P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}},{i + 1}}} & {{Eq}.\mspace{14mu}(2)}\end{matrix}$

In various embodiments, quantifying process 210 may receive normalizedoil volume 208 and normalized gas pressure 209 as one or more inputs.Quantifying process 210 may receive desired oil volume 230 and desiredgas pressure 231 as one or more inputs. Desired oil volume 230 anddesired gas pressure 231 may refer to a desired oil volume and desiredgas pressure, respectfully. Thus, desired gas pressure 231 maycorrespond with a desired number of moles of gas. Quantifying process210 may use equation 3 and equation 4 to calculate volume of oil loss(referred to herein as “oil loss”) 211 and number of moles of gas loss(referred to herein as “gas loss”) 212 (see step 702).

$\begin{matrix}{{\Delta V}_{{{oil}@20}{^\circ}\mspace{14mu}{C.}} = {V_{{oil},{nom}} - V_{{oil},{{m@20}{^\circ}\mspace{14mu}{C.}}}}} & {{Eq}.\mspace{14mu}(3)} \\{{\Delta\; n_{gas}} = {\frac{( {P_{{gas},{nom}} + 14.7} ) \times ( {V_{tot} - V_{{oil},{nom}}} )}{R \times ( {20 + 273} ) \times {Z( {P_{{gas},{nom}},{20{^\circ}\mspace{14mu}{C.}}} )}} - \frac{( {P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}}} + 14.7} ) \times ( {V_{tot} - V_{{oil},{{m@20}{^\circ}\mspace{14mu}{C.}}}} )}{R \times ( {20 + 273} ) \times {Z( {P_{{gas},{{m@20}{^\circ}\mspace{14mu}{C.}}},{20{^\circ}\mspace{14mu}{C.}}} )}}}} & {{Eq}.\mspace{14mu}(4)}\end{matrix}$

Oil loss 211 may comprise a value which represents the amount of oilthat a shock strut has lost since its last servicing. Stated anotherway, oil loss 211 may comprise a value which represents the difference,in volume of oil, between a desired volume of oil and a current volumeof oil in a shock strut. Gas loss 212 may comprise a value whichrepresents the amount of gas that a shock strut has lost since its lastservicing. Stated another way, gas loss 212 may comprise a value whichrepresents the difference, in number of moles of gas, between a desirednumber of moles of gas and a current number of moles of gas in a shockstrut.

As illustrated in FIG. 2, display process 214 includes first oildecision 216, second oil decision 220, first gas decision 218, secondgas decision 222, no action display process 224, warning display process226, and service display process 228.

With reference to FIG. 2 and FIG. 3, display process 214 may be used togenerate a display such as, for example, display 300 provided in FIG. 3.First oil decision 216 may determine if oil loss 211 is above a secondoil threshold. If oil loss 211 is above the second oil threshold, thenservice display process 228 may generate a warning signal such as, forexample, “oil servicing is required” as illustrated by oil servicingsignal 324 in FIG. 3, or the like (see step 703). If oil loss 211 is notabove the second oil threshold, then second oil decision 220 may decideif oil loss 211 is above a first oil threshold. If oil loss 211 is abovethe first threshold, then service display process 226 may generate awarning signal such as, for example, “schedule for oil servicing”, orthe like. If oil loss 211 is not above the first oil threshold, then noaction display process 224 may be configured to not generate anysignals, or may be configured to generate a signal indicating the thatoil level is acceptable, or the like.

First gas decision 218 may decide if gas loss 212 is above a second gasthreshold. If gas loss 212 is above the second gas threshold, thenservice display process 228 may generate a warning signal such as, forexample, “gas servicing is required”, or the like (see step 703). If gasloss 212 is not above the second gas threshold, then second gas decision222 may decide if gas loss 212 is above a first gas threshold. If gasloss 212 is above the first gas threshold, then service display process226 may generate a warning signal such as, for example, “schedule forgas servicing” as illustrated by gas service signal 322 in FIG. 3, orthe like. If gas loss 212 is not above the first gas threshold, then noaction display process 224 may be configured to not generate anysignals, or may be configured to generate a signal indicating that thegas level is acceptable, or the like.

In accordance with various embodiments, display process 214 may includeone or more oil decisions, one or more gas decisions, and one or moredisplay processes. Accordingly, display process 214 may use one or morethreshold values to determine the type of display to generate. Forexample, many threshold values may be used to display a percentagerepresenting the volume of oil and a percentage representing the volumeof gas remaining in a shock strut, or the like.

With reference to FIG. 3, display 300 is illustrated, in accordance withvarious embodiments. As illustrated in FIG. 3, display 300 located on ahandheld device 302. However, display 300 may be in any location suchas, for example, an aircraft. With momentary reference to FIG. 2, all orpart of loss detection process 200 may be located on handheld device302. Thus, handheld device 302 may include a computer readable medium.Handheld device 302 may comprise a controller.

In various embodiments, display 300 may include various selectable tabssuch as selectable tab 304, selectable tab 306, selectable tab 308,selectable tab 310, and selectable tab 312. Selectable tab 310 may beselected to display parameters such as gas pressure 205, gas temperature314, shock strut stroke 316, gas loss 212, gas service signal 322, oilservice signal 324, and the like. With momentary reference to FIG. 2, invarious embodiments, gas service signal 322 may be generated in responseto a change in gas pressure located in a shock strut. Stated anotherway, gas service signal 322 may change in response to the value of oilloss 211 and/or gas loss 212 increasing above an oil and/or a gasthreshold value. In various embodiments, oil service signal 324 maychange in response to a change in oil volume located in a shock strut.Stated another way, oil service signal 324 may change in response to thevalue of oil loss 211 increasing above an oil threshold value.

With respect to FIG. 4, elements with like element numbering, asdepicted in FIG. 3, are intended to be the same and will not necessarilybe repeated for the sake of clarity.

With reference to FIG. 4, display 400 is illustrated, in accordance withvarious embodiments. Display 400 may be similar to display 300 of FIG.3. Selectable tab 312 may be selected to display oil and/or gasservicing instructions. As illustrated in FIG. 4, display 400 includes aselectable oil adjustment start tab, a selectable oil adjustment finishtab, a selectable gas adjustment start tab, a selectable gas adjustmentfinish tab, and an indication signal 440. However, any display may beused to implement the oil and/or gas level adjustment processes asdescribed herein. In various embodiments, the oil level adjustmentprocess may be followed by the gas level adjustment process.

With further reference to FIG. 8, a method or process 800 for servicingoil volume within a shock strut is provided. With further reference toFIG. 5, selectable start tab 422 may be selected by an operator to startor initiate an oil level adjustment process 500. In various embodiments,oil level adjustment process 500 may comprise system programinstructions and/or controller instructions. Oil level adjustmentprocess 500 may be located on handheld device 302. However, it iscontemplated that oil level adjustment process 500 may be located on acontroller located on an aircraft or other vehicle.

In various embodiments, oil level adjustment process 500 may includestart decision 502, oil addition calculator 520, and comparator 530. Invarious embodiments, oil level adjustment process 500 may include finishdecision 522, update process 524, and memory 526. In variousembodiments, comparator 530 may include one or more IF logics. Asillustrated in FIG. 5, comparator 530 includes first IF logic 534,second IF logic 536, third IF logic 538, and fourth IF logic 540.

Start decision 502 may determine if an operator has indicated to startan oil level adjustment process. For example, an operator may selectselectable start tab 422 and in response, start decision 502 mayindicate to start oil level adjustment process 500. In variousembodiments, oil addition calculator 520 may quantify the volume of oiladded to a shock strut in response to start decision 502 being true. Oiladdition calculator 520 may receive initial gas pressure 518, initialgas temperature 516, and initial shock strut stroke 514 from initialparameter retriever 506. In various embodiments, initial parameterretriever 506 may acquire initial gas pressure 518, initial gastemperature 516, and initial shock strut stroke 514 from a shock strutservicing monitoring system such as SSSMS 202 (see FIG. 2). However,initial parameter retriever 506 may acquire initial gas pressure 518,initial gas temperature 516, and initial shock strut stroke 514 from anysuitable location. Initial parameter retriever 506 may be configured toacquire initial gas pressure 518, initial gas temperature 516, andinitial shock strut stroke 514. Initial gas pressure 518, initial gastemperature 516, and initial shock strut stroke 514 may be the gaspressure, gas temperature, and shock strut stroke at the onset of theoil level adjustment process 500, respectively. Oil addition calculator520 may receive updated gas pressure 512, updated gas temperature 510,and updated shock strut stroke 508 from updating parameter retriever504. Updating parameter retriever may acquire updated gas pressure 512,updated gas temperature 510, and updated shock strut stroke 508 at apre-determined rate, such as 10 Hz, for example. Updated gas pressure512, updated gas temperature 510, and updated shock strut stroke 508 maybe the gas pressure, gas temperature, and shock strut stroke,respectively, as measured by the shock strut sensors during the oillevel adjustment process 500.

Oil addition calculator 520 may use equation 5 through equation 9 tocalculate the volume of added oil (also referred to herein as a firstfluid level) 521 to a shock strut (see step 801). Volume of added oil521 may be the equivalent volume of oil added to a shock strut at apredetermined temperature such as twenty degrees Celsius, for example.

$\begin{matrix}{V_{{oil},{0@{\hat{T}}_{{gas},0}}} = {( {V_{{oil},{nom}} - {\Delta\; V_{{{oil}@20}{^\circ}\mspace{14mu}{C.}}}} )( {1 + {\alpha \times {dT} \times {{sign}( {{\hat{T}}_{{gas},0} - {20{^\circ}\mspace{14mu}{C.}}} )}}} )^{\frac{{20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{{gas},0}}}}}{dT}}}} & {{Eq}.\mspace{14mu}(5)} \\{V_{{gas},{0@{\hat{T}}_{{gas},0}}} = {V_{{tot},{{in} - {air}}} - {A \times {\hat{S}}_{0}} - V_{{oil},{0@{\hat{T}}_{{gas},0}}}}} & {{Eq}.\mspace{14mu}(6)} \\{\frac{V_{{gas},{0@{\hat{T}}_{{gas},0}}}( {{\hat{P}}_{{gas},0} + 14.7} )}{{\hat{T}}_{{gas},0} \times {Z( {{\hat{P}}_{{gas},0},{\hat{T}}_{{gas},0}} )}} = \frac{\begin{matrix}( {V_{{tot},{{in} - {air}}} - {A \times \hat{S}} - V_{{oil},{{0@\hat{T}} - {gas}},0} - {\Delta\; V_{{oil} - {{added}@{\hat{T}}_{{gas},0}}}}} ) \\( {{\hat{P}}_{gas} + 14.7} )\end{matrix}}{{\hat{T}}_{gas} \times {Z( {{\hat{P}}_{gas},{\hat{T}}_{gas}} )}}} & {{Eq}.\mspace{14mu}(7)} \\{{\Delta\; V_{{oil} - {{added}@{\hat{T}}_{{gas},0}}}} = {( {V_{{tot},{{in} - {air}}} - {A \times \hat{S}} - V_{{oil},{{0@\hat{T}} - {gas}},0}} ) - ( {\frac{{\hat{T}}_{gas} \times {Z( {{\hat{P}}_{gas},{\hat{T}}_{gas}} )}}{( {{\hat{P}}_{gas} + 14.7} )} \times \frac{V_{{gas},{0@{\hat{T}}_{{gas},0}}}( {{\hat{P}}_{{gas},0} + 14.7} )}{{\hat{T}}_{{gas},0} \times {Z( {{\hat{P}}_{{gas},0},{\hat{T}}_{{gas},0}} )}}} )}} & {{Eq}.\mspace{14mu}(8)} \\{{\Delta\; V_{{oil} - {{added}@20}}} = {\Delta\;{V_{{oil} - {{added}@{\hat{T}}_{{gas},0}}}( {1 + {\alpha \times {dT} \times {{sign}( {20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{gas}}}} )}}} )}^{\frac{{20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{gas}}}}}{dT}}}} & {{Eq}.\mspace{14mu}(9)}\end{matrix}$

In various embodiments, comparator 530 may compare added oil 521 withone or more servicing thresholds. Comparator 530 may receive computedoil loss 528 from memory 626. In various embodiments, computed oil loss528 may be equal to oil loss 211 of FIG. 2. Thus, as an operator addsoil to a shock strut, comparator 530 may actively compare updated addedoil 521 with one or more servicing thresholds to indicate to theoperator when to stop or slow the process of filling the shock strutwith oil as described herein. In various embodiments, added oil 521 maycomprise a value, data point, datum, or the like.

Accordingly, as illustrated in FIG. 5, first IF logic 534 may determineif desired oil volume 230 minus oil loss 211 plus added oil 521 is lessthan or equal to a second oil volume threshold. The volume of oil in theshock strut may be less than a desired volume in response to first IFlogic 534 being true. Thus, comparator 530 may generate a datum (alsoreferred to herein as a first datum) in response to first IF logic 534being true (see step 802). Accordingly, the datum may indicate to anindicator, such as indicator 542 for example, to indicate to an operatorto continue adding oil to a shock strut. For example, a datum maycomprise a signal, data point, value, or the like which indicates to acontroller that first IF logic 534 is true. An indicator 542 mayindicate to the operator to continue adding oil to the shock strut inresponse to first IF logic 534 being true. Thus, a shock strut mayreceive oil in response to first IF logic 534 being true (see step 803).

As illustrated in FIG. 5, second IF logic 536 may determine if desiredoil volume 230 minus oil loss 211 plus added oil 521 is less than orequal to a first oil volume threshold and is greater than the second oilvolume threshold. The volume of oil in the shock strut may be less thana desired volume in response to IF logic 536 being true. An indicator544 may indicate to the operator to continue adding oil to the shockstrut in response to second IF logic 536 being true. An indicator 544may indicate to the operator to continue adding oil to the shock strutat a slower rate in response to second IF logic 536 being true.

As previously mentioned, oil addition calculator 520 may calculate thevolume of added oil 521 to a shock strut as oil is added to a shockstrut. Accordingly, an updated value of added oil (also referred toherein as a second fluid level) 521 may be calculated by oil additioncalculator 520 (see step 804). In various embodiments, the value ofadded oil 521 may increase as oil is added to a shock strut.

As illustrated in FIG. 5, third IF logic 538 may determine if desiredoil volume 230 minus oil loss 211 plus added oil 521 is less than orequal to desired oil volume 230 scaled by a factor such as, for example,1.02 and is greater than the first oil volume threshold. The volume ofoil in the shock strut may be equal to a desired volume in response tothird IF logic 538 being true. Thus, comparator 530 may generate a datum(also referred to herein as a second datum) in response to third IFlogic 538 being true (see step 805). Accordingly, the datum may indicateto an indicator, such as indicator 546 for example, to indicate to anoperator to stop adding oil to a shock strut. An indicator 546 mayindicate to the operator to stop adding oil to the shock strut inresponse to third IF logic 538 being true. Thus, a shock strut may stopfrom receiving oil in response to third IF logic 538 being true.

As illustrated in FIG. 5, fourth IF logic 540 may determine if desiredoil volume 230 minus oil loss 211 plus added oil 521 is greater thandesired oil volume 230 scaled by a factor such as, for example, 1.02.The volume of oil in the shock strut may be greater than a desiredvolume in response to fourth IF logic 540 being true. An indicator 548may indicate to the operator that the shock strut has been over filledwith oil in response to fourth IF logic 540 being true.

An operator may be instructed to stop adding oil to a shock strut atwhich moment the operator would stop from adding oil to the shock strutin response to third IF logic 538 being true. The operator may thenindicate to oil level adjustment process 500 that the oil volumeadjustment process is finished by, for example, selecting selectablefinish tab 424. Subsequently, finish decision 522 may determine if thefinish tab 424 is selected and indicate to update process 524 to updateand store a new oil volume (also referred to herein as a final fluidlevel) 525 to memory 526 (see step 806) in response to finish tab 424being selected. New oil volume 525 may be calculated by update process524 by taking desired oil volume 230 minus oil loss 211 plus added oil521.

In various embodiments, indicator 542, indicator 544, indicator 546, andindicator 548 may be located on display 400 via indicator 440, forexample. Thus, indicator 440 may indicate when to stop adding oil to ashock strut. Accordingly, oil level adjustment process 500 may generatean indicator corresponding to added oil 521.

With reference to FIG. 9, a method or process 900 for servicing gaswithin a shock strut is provided. With reference to FIG. 4 and FIG. 6,selectable start tab 426 may be selected by an operator, to start orinitiate a gas level adjustment process 600. In various embodiments, gaslevel adjustment process 600 may comprise system program instructionsand/or controller instructions. Gas level adjustment process 600 may belocated on handheld device 302. However, it is contemplated that gaslevel adjustment process 600 may be located on a controller located onan aircraft or other vehicle. In various embodiments, gas leveladjustment process 600 may be similar to oil level adjustment process500.

In various embodiments, gas level adjustment process 600 may includestart decision 602, gas addition calculator 620, and comparator 630. Invarious embodiments, gas level adjustment process 600 may include finishdecision 622, update process 624, and memory 626. In variousembodiments, comparator 630 may include one or more IF logics. Asillustrated in FIG. 6, comparator 630 includes first IF logic 634,second IF logic 636, third IF logic 638, and fourth IF logic 640.

Start decision 602 may determine if an operator has indicated to start agas level adjustment process. For example, an operator may selectselectable start tab 426 and in response, start decision 602 mayindicate to start gas level adjustment process 600. In variousembodiments, gas addition calculator 620 may quantify the number ofmoles of gas added to a shock strut in response to start decision 602being true. Gas addition calculator 620 may receive initial gas pressure618, initial gas temperature 616, and initial shock strut stroke 614from initial parameter retriever 606. Initial gas pressure 618, initialgas temperature 616, and initial shock strut stroke 614 may be the gaspressure, gas temperature, and shock strut stroke at the onset of thegas level adjustment process 600, respectively. Gas addition calculator620 may receive updated gas pressure 612, updated gas temperature 610,and updated shock strut stroke 608 from updating parameter retriever604. Updating parameter retriever may acquire updated gas pressure 612,updated gas temperature 610, and updated shock strut stroke 608 at apre-determined rate, such as 10 Hz, for example. Updated gas pressure612, updated gas temperature 610, and updated shock strut stroke 608 maybe the gas pressure, gas temperature, and shock strut stroke,respectively, as measured by the shock strut sensors during the gaslevel adjustment process 600. Gas addition calculator 620 may useequation 10 through equation 13 to calculate the number of moles ofadded gas (also referred to herein as a first fluid level) 621 to ashock strut (see step 901).

$\begin{matrix}{V_{{oil},{0@{\hat{T}}_{{gas},0}}} = {( {V_{{oil},{nom}} - {\Delta\; V_{{{oil}@20}{^\circ}\mspace{14mu}{C.}}}} )( {1 + {\alpha \times {dT} \times {{sign}( {{\hat{T}}_{{gas},0} - {20{^\circ}\mspace{14mu}{C.}}} )}}} )^{\frac{{20{^\circ}\mspace{14mu}{C.{- {\hat{T}}_{{gas},0}}}}}{dT}}}} & {{Eq}.\mspace{14mu}(10)} \\{V_{{gas},{0@{\hat{T}}_{{gas},0}}} = {V_{{tot},{{in} - {air}}} - {A \times {\hat{S}}_{0}} - V_{{oil},{0@{\hat{T}}_{{gas},0}}}}} & {{Eq}.\mspace{14mu}(11)} \\{n_{0} = \frac{( {{\hat{P}}_{{gas},0} + 14.7} ) \times V_{{gas},{0@{\hat{T}}_{{gas},0}}}}{{\hat{T}}_{{gas},0} \times {Z( {{\hat{P}}_{{gas},0},{\hat{T}}_{{gas},0}} )} \times R}} & {{Eq}.\mspace{14mu}(12)} \\{{\Delta\; n_{{gas},{added}}} = {\frac{( {{\hat{P}}_{gas} + 14.7} ) \times ( {V_{{gas},{0@{\hat{T}}_{{gas},0}}} + {A( {\hat{S} - {\hat{S}}_{0}} )}} )}{{\hat{T}}_{gas} \times {Z( {{\hat{P}}_{gas},{\hat{T}}_{gas}} )} \times R} - n_{0}}} & {{Eq}.\mspace{14mu}(13)}\end{matrix}$

In various embodiments, comparator 630 may compare number of moles ofadded gas 621 with one or more servicing thresholds. Comparator 630 mayreceive computed gas loss 628 from memory 626. In various embodiments,computed gas loss 628 may be equal to gas loss 212 of FIG. 2. Thus, asan operator adds gas to a shock strut, comparator 630 may activelycompare updated number of moles of added gas 621 with one or moreservicing thresholds to indicate to the operator when to stop or slowthe process of filling the shock strut with gas as described herein (seestep 903 and step 904). In various embodiments, number of moles of addedgas 621 may comprise a value, data point, or the like.

Accordingly, as illustrated in FIG. 6, first IF logic 634 may determineif a desired number of moles of gas minus number of moles of gas loss212 plus number of moles of added gas 621 is less than or equal to asecond gas number of moles threshold. The number of moles of gas in theshock strut may be less than a desired level in response to first IFlogic 634 being true. Thus, comparator 630 may generate a datum (alsoreferred to herein as a first datum) in response to first IF logic 634being true (see step 902). Accordingly, the datum may indicate to anindicator, such as indicator 642 for example, to indicate to an operatorto continue adding gas to a shock strut. For example, a datum maycomprise a signal, data point, value, or the like which indicates to acontroller that first IF logic 634 is true. An indicator 642 mayindicate to the operator to continue adding gas to the shock strut inresponse to first IF logic 634 being true. Thus, a shock strut mayreceive gas in response to first IF logic 634 being true (see step 903).

As illustrated in FIG. 6, second IF logic 636 may determine if a desirednumber of moles of gas minus number of moles of gas loss 212 plus numberof moles of added gas 621 is less than or equal to a first gas levelthreshold and is greater than the second gas level threshold. The numberof moles of gas in the shock strut may be less than a desired level inresponse to second IF logic 636 being true. An indicator 644 mayindicate to the operator to continue adding gas to the shock strut inresponse to second IF logic 636 being true. An indicator 644 mayindicate to the operator to slow the rate at which the operator isadding gas to the shock strut in response to second IF logic 636 beingtrue.

As previously mentioned, gas addition calculator 620 may calculate thenumber of moles of added gas 621 to a shock strut as gas is added to theshock strut. Accordingly, an updated value of added gas (also referredto herein as a second fluid level) 621 may be calculated by gas additioncalculator 620 (see step 904). In various embodiments, the value ofnumber of moles of added gas 621 may increase as gas is added to a shockstrut.

As illustrated in FIG. 6, third IF logic 638 may determine if a desirednumber of moles of gas minus number of moles of gas loss 212 plus numberof moles of added gas 621 is less than or equal to a desired number ofmoles of gas scaled by a factor such as, for example, 1.02 and isgreater than the first gas level threshold. The number of moles of gasin the shock strut may be equal to a desired level in response to thirdIF logic 638 being true. Thus, comparator 630 may generate a datum (alsoreferred to herein as a second datum) in response to third IF logic 638being true (see step 905). Accordingly, the datum may indicate to anindicator, such as indicator 646 for example, to indicate to an operatorto stop adding gas to a shock strut. An indicator 646 may indicate tothe operator to stop adding gas to the shock strut in response to thirdIF logic 638 being true. Thus, a shock strut may stop from receiving gasin response to third IF logic 638 being true.

As illustrated in FIG. 6, fourth IF logic 640 may determine if a desirednumber of moles of gas minus number of moles of gas loss 212 plus numberof moles of added gas 621 is greater than a desired number of moles ofgas scaled by a factor such as, for example, 1.02. The number of molesof gas in the shock strut may be greater than a desired level inresponse to fourth IF logic 640 being true. An indicator 648 mayindicate to the operator that the shock strut has been over filled withgas in response to fourth IF logic 640 being true.

An operator may be instructed to stop adding gas to a shock strut atwhich moment the operator would stop from adding gas to the shock strutin response to third IF logic 638 being true. The operator may thenindicate to gas level adjustment process 600 that the gas volumeadjustment process is finished by, for example, selecting selectablefinish tab 428. Subsequently, finish decision 622 may determine if thefinish tab 428 is selected and indicate to update process 624 to updateand store a new gas number of moles (also referred to herein as a finalfluid level) 625 to memory 626 (see step 906) in response to finish tab428 being selected. New gas number of moles 625 may be calculated bytaking a desired number of moles of gas minus number of moles of gasloss 212 plus number of moles of added gas 621.

In various embodiments, indicator 642, indicator 644, indicator 646, andindicator 648 may be located on display 400 via indicator 440, forexample. Thus, indicator 440 may indicate when to stop adding gas to ashock strut. Accordingly, gas level adjustment process 600 may generatean indicator corresponding to number of moles of added gas 621.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A shock strut servicing assistance system,comprising: a controller including a display; and a tangible,non-transitory memory configured to communicate with the controller, thetangible, non-transitory memory having instructions stored thereon that,in response to execution by the controller, cause the controller toperform operations comprising: calculating, by the controller, a firstfluid level at a first time based upon at least an initial gas pressure,an initial gas temperature, and an initial gas strut stroke position;generating, by the controller, a first datum corresponding to the firstfluid level; sending, by the controller, the first datum to a display;receiving, by the controller, an updated gas pressure, an updated gastemperature, and an updated shock strut stroke position, correspondingto a fluid moved into the shock strut subsequent to the first fluidlevel being calculated; calculating, by the controller, a second fluidlevel at a second time based upon at least the initial gas pressure, theinitial gas temperature, the initial shock strut stroke position, theupdated gas pressure, the updated gas temperature, and the updated shockstrut stroke position; generating, by the controller, a second datumcorresponding to the second fluid level; storing, by the controller, afinal fluid level; and sending, by the controller, the second datum tothe display.
 2. The shock strut servicing assistance system of claim 1,wherein the controller is in electronic communication with a shock strutservicing monitoring system.
 3. The shock strut servicing assistancesystem of claim 1, wherein an indication is displayed on the display inresponse to at least one of the first datum or the second datum.
 4. Theshock strut servicing assistance system of claim 1, wherein the seconddatum is generated in response to the second fluid level being greaterthan a threshold value.
 5. The shock strut servicing assistance systemof claim 1, wherein the first fluid level and the second fluid levelcorresponds to at least one of a volume of a fluid added to a shockstrut during service or a number of moles of the fluid added to theshock strut during service.
 6. The shock strut servicing assistancesystem of claim 1, wherein the fluid comprises at least one of oil orgas.